The newer UHF toll tags are around 915MHz, but antennas printed on plastic is still pretty big -- they need to be to get enough power to run the chip. I have found a couple of useful links:
Plenty of literature there. Without a battery, there is just not enough power for any kind of processing. The communications protocol has a bit of smarts for separating multiple chips responding to a transponder. It's just for ID purposes. Programming flash will takes lots and lots of power (milliwatts), so the ID is fixed at the time it is affixed.
The newer UHF toll tags are around 915MHz, but antennas printed on plastic is still pretty big -- they need to be to get enough power to run the chip. I have found a couple of useful links:
https://en.wikipedia.org/wiki/EZ_TAG
https://transcore.com/literature
Plenty of literature there. Without a battery, there is just not enough power for any kind of processing. The communications protocol has a bit of smarts for separating multiple chips responding to a transponder. It's just for ID purposes. Programming flash will takes lots and lots of power (milliwatts), so the ID is fixed at the time it is affixed.